1. Field of the Invention
The present invention relates to an improved printer for exposing and printing a photosensitive color printing paper and more particularly relates to a printer which is improved such that printing operation is performed with a certain color balance properly maintained by means of a cut filter assembly comprising three cut filters of a yellow filter, magenta filter and cyan filter, wherein two light beam flux reducing filters contained in said cut filter assembly are put in use during the printing process under such an operation condition that the intensity of a light beam coming up from a light source for exposure is previously magnified to a certain level so as to properly fit a negative color film which has an overexposure when a photograph is taken, said light beam flux reducing filters being adapted to be protruded into a light beam passage prior to opening a shutter, whereby quick printing is ensured with the minimized fluxtuation in printing time, maintaining an excellent color balance irrespective of any excessive or insufficient exposure to which the negative color film is subjected.
2. Description of the Prior Art
As will be well known, the conventional printer for exposing and printing a photosensitive printing paper (hereinafter referred to as printing paper) for a negative color film is commonly equipped with a cut filter assembly comprising a yellow filter, magenta filter and cyan filter in order to ensure a color balance.
Usually, the above-described conventional printer which is widely used throughout the relevant industries at present takes at least about 0.08 second until successive operations of the three cut filters are initiated and completed by means of a plurality of color photo sensors which are adapted to detect a light beam which has passed through the negative color film.
Due to an overexposure or underexposure to which a color photographic film is subjected when a photograph is taken there is caused a wide range of fluctuation in printing time, that is, exposure time for the printing paper. Thus, for instance, a negative color film which has had an underexposure due to a shortage in exposing time when taking a photograph should have a short printing time which is restricted by the minimum operation time required for operating the cut filter assembly. On the other hand, with respect to a negative color film which has had an overexposure due to an excessive exposing time when taking a photograph, an exposure is applied by magnifying the intensity of a light beam from a light source in order to reduce the printing time which usually amounts to several seconds. This causes the negative color film which has had an underexposure to be exposed to the printing light beam for a shorter time than the minimum operation time of the cut filter assembly. Thus it has been pointed out as drawbacks or disadvantages with the conventional printer that excessive exposure is applied and thereby printing is performed with a color balance and contrast maintained in an undesirable manner.
In order to obviate the drawbacks or disadvantages as described above, proposals have been heretofore made such that a light beam flux reducing filter is put in use when it is found that a negative color film has an underexposure, whereas printing time is prolonged when it is found that a negative color film has an overexposure, provided that the intensity of a light beam from a light source incorporated in the printer is predetermined under such an operation condition that a printing paper is exposed to a light beam with the use of a negative color film which has had a normal exposure and development.
However, the proposals as described above have an unavoidable drawback that a longer time is taken for printing when it is found that a negative color film has an overexposure. The aforesaid drawback becomes more and more remarkable as a demand for photographic film has been substantially increased due to the latest quick and wide spread of cameras. Hence, sincere requests have been raised from the users of printers for obviating these drawbacks and disadvantages and then improving their operational performances.